It's hard to
believe that it has been three years since the introduction
of the first AMD
Athlons. To celebrate the occasion, AMD
has unveiled two new processors in their Athlon XP lineup,
the 2600+ and the 2400+. The Athlon XP 2600+ is
clocked at 2133MHz, and the 2400+ is clocked at an even
2GHz, making these two new processors the first AMD CPUs to
officially break the 2GHz barrier. The road to 2GHz
was a rough one for AMD though. They may have beaten
Intel to the 1GHz mark in the Pentium III days, but with the
release of the Pentium 4 Intel has been able to increase
clock speeds almost at will. This put AMD in a tough
spot, forcing them to find ways to squeeze more performance
out of the venerable Athlon. The "Thunderbirds" and
"Palominos" came and went, then last June the
"Thoroughbreds" arrived on the scene. With these
latest CPUs, AMD has enhanced the "Thoroughbred" core,
giving them the ability to hit much higher clock speeds than
the original stepping. We were lucky enough to get our
hands on one of AMD's latest flagship processor, the Athlon
XP 2600+, and have put it through its paces for you today...

Specifications of the AMD Athlon XP 2600+
Processor

A Metal Layer
Here...Some Decoupling Caps There...

The Athlon XP
2600+ we received for testing was packaged in brown organic
material (high-resolution scans below). AMD will eventually
produce all of their CPUs using green packaging. The
coloring has absolutely no effect on performance though, so
don't fret if you order one and it isn't green!

CLICK ANY IMAGE FOR
ENLARGED VIEW

Key Architectural Features of
the AMD Athlon XP Processor:

QuantiSpeed
Architecture for enhanced performance

Nine-issue
superpipelined, superscalar x86 processor microarchitecture
designed for high performance

Multiprocessing
support: point-to-point topology, with number of processors
in SMP systems determined by chipset implementation
Support for 24 outstanding transactions per processor

Other Architectural Elements:

The AMD Athlon
XP processor with performance-enhancing cache memory
features 64K instruction and 64K data cache for a total of
128K L1 cache. 256K of integrated, on-chip L2 cache
for a total of 384K full-speed, on-chip cache.

Socket A
infrastructure designs are based on high-performance
platforms and are supported by a full line of optimized
infrastructure solutions (chipsets, motherboards, BIOS).
Available in Pin Grid Array (PGA) for mounting in a socketed
infrastructure Electrical interface compatible with 266MHz
AMD Athlon XP system buses, based on Alpha EV6 bus protocol

If you read any
of the AMD Athlon XP 2200+ reviews posted when that
processor launched, you were probably a bit disappointed in
the overclocking results reported by most of the on-line
publications, including ours. After those reviews went live,
we began to wonder if the new "Thoroughbred" core would be
able scale to clock speeds approaching 2GHz. Well, the
resounding answer is YES! But how did AMD do it when the
2200+ was barely hitting 1900MHz? Well, we'll let them tell
you. Here's a quote taken directly from AMD...

AMD has implemented a mask set
change that allowed them to improve signaling into the
processor. If you look at the chart and illustrations
above, you'll notice that the changes were fairly
significant. The new AIUAB stepping of the "Thoroughbred"
core actually incorporates about 100K more on-die
transistors, roughly the amount of transistors that made
up a complete 80286 CPU! The additional transistors
slightly increased the die size to 84 square millimeters,
up from 80 in the original "Thoroughbreds". These changes
probably cost AMD a pretty penny though, a .13 micron mask
set could cost as much as $1 million US is some
circumstances. It was money well spent in our opinion
though. As you'll see later on, this CPU turned out to be
a real screamer...